Corrosion-resisting refractory.



PAUL RALPH HERSHMAN, CHICAGO, ILLINOIS.

'. connosIon-nissrs'rme anrnno'ronr.

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No Drawing.

To all whom it may concern:

Be it knownthat I, PAUL R. HERSHMAN,

a citizen of the Empire of Austria-Hungary, residing in Chicago, county of Cook, State of Illinois, have invented certain new and useful Improvements in Corrosion-Resisting Refractory; and I do hereby declare the following to be a full, clear, and exact description of the invention, such as will enable others skilled in the art to which. it appertains to make and use the same.

My invention relates to a new and useful composition of matter which, when entbodied in the form of bricks or slabs, solid;

or hollow, furnace linings, flue linings, and the like is highly tendency of furnace gases and which has exceedingly high refractory properties which permit it to be employed where temperatures in excess of 2000 C. prevail. Its resistivity to the corroding tendency of gases is so high that it is unaffected by such a powerful corrodent as hydrofluoric acid andis well adapted to'serve as a liner for flues,. furnaces, containers and vessels generally exposed to the action of hydrofluoric acid.

The heat-resisting and corrosion-resisting material (whether furnace lining, brick, flue lining, or the like) produced in accordance with my invention contains aluminum and." carbon, the carbon present being in proportion less than that required for converting the metal into aluminum carbid. In some the aluminiferous material employed in the manufacture of the product instances,

what is known as alu fine particles of the grind ng or may be, for instance, minum dust, that is to say, aluminum obtained from burring of aluminum in work-shop operations, and whichconsists in part, of filings, shavings, and the like, and which may incidentally contain a certain lesser amount of like particles of copper, iron, etc. This material, which usually contains as high as from -95% metallic aluminum is relatively cheap as compared with the pure metal and, for that reason, is more available commercially for the purpose than the pure metal itself.

Another and the preferred source of the aluminiferous ingredient of the product is aluminum oxid, that is to say, alumina, and, preferably, calcined alunite, (substantially deprived of its alkali content) which I have found particularly adapted'for the purpose.

resistant to the corroding Aluminum oxid is a still cheaper product than the aluminum dust hereinbefore referred to and has certain specific advantages which Wlll be hereinafter pointed out. Whether aluminum dust or aluminum oxid is employed, as the case may be, I prefer to Specification of Letters Patent. 1 Patgntfidl @ept, t2, jlgjllafi, Application filed August 9,1915. seria no. eases.

finely divided carbon (as, for instance, finely ground coke) terial, together with a sufficient amount of tar or glue to serve as a binder, the mass thus formed being then briqueted in the usual way. As hereinbefore indicated, the amount of carbon represented by the finely with the aluminiferous ma ground coke. and by the tar or other earbonaceous body employed as the binder, is

,taken in proportion insufficient to convert the entire mass of the aluminum into aluminum carbid.

The purposes of the invention will be best subserved by conducting the subsequent heating of the bricks, necessary for the manufacture of the final product, in such manner as to avoid, as far as possible, the occurrence of particles of metallic aluminum throughout'the brick. This is readily possible when alumina, and particularly calcined alunite, is the aluminiferous material employed. In

such case, I add to the alumina, 10-30% of its weight of finely ground coke, together with the quantity of tar required as a binder, and, after briqueting the mass, I subject the briquet to a slow distillation, raising it in temperature gradually up to about 600 C.

until it has parted with its volatile hydrocarbons and is substantially dry. I then subject the briquets to a gradually increasing heat, preferably in an electric furnace,

7 this additional heat rising by slow increments up to a minimum of say 1500 (3.,

but preferably as high as 2200 C., during a furnace treatment of six hours or more, according to the dimensions of the brick. Care should be taken not to speed up the heating operations nor to increase the dcgree of temperature employed other than gradually; otherwise the tendency would be toward the production of metal instead of i the refractory and corrosion-resisting brick desired. If the operation is carrie on as described, the resultant product will be bricks of considerable density and of fairly ice I IIW I promptly to the moving currents of air and 21. gas traversing the checker-work. The mod- Tera te coefficient of shrinkage of-the finished or mtroducing into the bonates which would Idioxid 4O the briquets may be raised to the desistivity' to heat is bricks likewise adapts them particularly Well to metallurgical uses, but, more especially they are of value for the reason that they are found to withstand temperatures ofand even in excess of 2200 rioration or deformation and to-resist (35rrosion even at these high temperatures.

here the aluminum .dust is used. as the aluminiferous material, the same relative proportion of finely'ground coke may be employed, together with a binder such as tar or glue, and the briqueted material is to be heated with the same precautions as to duration of crease in temperature, as hereinbefore described. In this case the final roduct' is distinctly less dense, its structure eing rela tively porousthroughout. So also, its reinferior to that of the dense brick made from the as the starting point. For certain uses, however, its porosity is a feature of advantage,-and even this characteristic may be producedin the brick made from aluminum OXld by the employment of such expedients as introducing into the aluminum oxid briquet particles of straw, which would be burned out in the furnacing of the brick,

give off their carbon during the furnacing operation. may say further that in heating the briguets to produc'ethe refractory and corroslon-resisting product desired, I prefer to. do so in an atmosphere of gases containing practically no free oxygen, for instance, producer gas. For small outputs, it will be convenient to heat the briquets either in an electric tube furnace, that is to say, a furnace consisting of a tube of carbon traversed by an electric current; or by inth sertingthem within a receptacle heated to a high temperature by the passage of an electric current through a solid resistor traversing its interior. For larger outputs,

sired temperature by passing heated gases through or over them while contained in a (3., without deteI- other hand, when aluminum oxid I This the heat and gradual inaluminum oxid in which the carb tion insufiicient to briquet suitable carout its suitable furnace chamber provided for the purpose.'

, As hereinbefore noted, the bricks made from aluminum dust are more porous than those made from the oxid. This is probably due to the fact that, in the bricks made from aluminum dust there is a con 'stant evaporation or sweating out of metallic aluminum, and, its exit from the material leaves the brick less dense; furthermore, more or less of the aluminum dust 1s seemingly converted into oxids by the' carbon monoxid .used, and this oxidation brings about an increase in volume. On the is employed as the aluminiferous material in the manufacture of bricks, the conditions of the operation tend to bring about the formation of aluminum sub -oxids, sub carbids, and the like,

actuallytakes place, be understood that I do not desire my vention to depend upon the correctness of this view and announce it merely as indicating the probable course of involved. I

,What I claim is 1. A corrosionaresisting refractory, comprising aluminifi'ous material and carbon,

on is present in proporconvert the entire mass of the aluminum into carbid; substantially as described.

2. A corrosion-resistingrefractory, com- 15 With a reduction in volum I regard s an explanation of. what c but It Wlll, ofivcours z in:

the reactions 1 prising alumina partly carburized through- 3. A corrosion-resisting refractory, comprising aluminiferous material and carbon fired at a temperature so high that the resultant product is practically inert to hydrofluoric acid; substantially as described.

corrosion-resisting refractory, comprising aluminiferou's. material and carbon fired at a temperature so high that the resultant product is practically drofluoric acid and in present in proportion insuflicient to convert e entire mass of the aluminum into carbid; substantially as described.

In testimony whereof I aflix my signature, in presence of two witnesses.

PAUL RALPH HERSHMAN. itnesses:

O. LOAQ, Jr.,' M. O. MYER.

mass; substantially as described. 1

inert to hy-' which the carbon is. 

